[CU2] Does your car have an issue with a "post-combustion detonation sound"?

**aaronng** · 21-05-2009 12:25 PM

Can someone who is currently using 98 RON and has pinging, do a test by running a full tank of 95 RON?

**Sludge** · 21-05-2009 12:26 PM

Originally Posted by SteveH

That sounds exactly the same as mine now. I only started to hear something around the 5,000 k mark. (Mine is a manual by the way) Mine sounds like a metallic rattle, almost like a cam chain rattling or something. (I know thats not what the noise is, just trying to describe the sound)

I found that my car was worse for both economy and rattling noise when I used Etahnol blended 95 octane petrol

Ethanol is a not a good mix with the CU2, so I'm told. In any event it is a false economy any saving is more than eaten away by the drop in economy. As I said before I'm sticking to the 95 octane. Sydney to Albury on 98 Octane 8.9 L/100k. Albury to Sydney, same driving conditions, 95 octane, 8.8 L/100k and no pinging!

**bk212** · 21-05-2009 01:05 PM

My CU2 has pinged consistently on 95 RON and 98 RON. Have tried full tanks of both - can't discern much difference in the pinging, it's there regardless of fuel type.

**aaronng** · 21-05-2009 02:14 PM

Originally Posted by bk212

My CU2 has pinged consistently on 95 RON and 98 RON. Have tried full tanks of both - can't discern much difference in the pinging, it's there regardless of fuel type.

Thanks. Now.... is anyone game to try 100 RON? It is expensive though.

**denot** · 22-05-2009 09:57 AM

I know ppl who has tried both 95 and 98 (at diff time) has combustion (aka pinging)problem. I want to know if anyone using 98 from the begining (except the fuel from dealer) has this problem as well?

**Bobjones** · 22-05-2009 10:27 AM

Well I run 98 ron, and I no longer have the "noise", actually, I have traced my noise to loose exhaust bolts, that I tightened myself and used aviation grade temp resitant locktite on...seems to not have come back. Maybe some others have this problem and NOT the post ignition issue???

**denot** · 22-05-2009 10:42 AM

Originally Posted by Bobjones

...Maybe some others have this problem and NOT the post ignition issue???

Now, that would be funny

**HVF00T** · 22-05-2009 02:10 PM

Originally Posted by Bobjones

Well I run 98 ron, and I no longer have the "noise", actually, I have traced my noise to loose exhaust bolts, that I tightened myself and used aviation grade temp resitant locktite on...seems to not have come back. Maybe some others have this problem and NOT the post ignition issue???

Fantastic.

Did you notice any specific bolts were loose, such as header bolts, or did you just tighten them all (headers, cat, muffler)? I'll take a look at mine on the weekend.

**biggame** · 23-05-2009 03:55 PM

Originally Posted by Bobjones

Well I run 98 ron, and I no longer have the "noise", actually, I have traced my noise to loose exhaust bolts, that I tightened myself and used aviation grade temp resitant locktite on...seems to not have come back. Maybe some others have this problem and NOT the post ignition issue???

Yeah, the kind of sounds a loose bolt would make is what i have... was it an obvious looselness? I too would like to know which bolts it was. If you could let us know it would be appreciated...

**Bobjones** · 25-05-2009 10:15 AM

I tightened everything, including heat sheilds, there is no "header" bolts as such as the exhaust manifold is cast into the head. I just went to town with the loctite...

**aaronng** · 25-05-2009 10:35 AM

Originally Posted by Bobjones

I tightened everything, including heat sheilds, there is no "header" bolts as such as the exhaust manifold is cast into the head. I just went to town with the loctite...

Did you check the spring loaded bolts between the header and the 2 cats?

**Bobjones** · 26-05-2009 09:05 AM

Originally Posted by aaronng

Did you check the spring loaded bolts between the header and the 2 cats?

Yes, they were still tight, however I did remove them and loctite them to. I am merely suggesting that people give it a go, seems that most "dealers" and their "technicians" will only find a fault if the computer tells them its there...